You'd like to think that Sebastian Vettel won't forget the keys to his Red Bull on Sunday. And in the very unlikely event that he finds the car sat on the grid but the battery is flat, well there's a good chance his garage crew will have a set of jump leads.

So that's the first two boxes ticked on the AA's most common list of breakdowns. The bad news for Vettel, however, is that his gleaming Formula One car is every bit as much at risk of the next two as any clapped out old Vauxhall Vectra.

Tyre issuess come third - and not even the Pirelli people with their multi-million pound development budgets can guarantee an F1 driver won't get a puncture. And then in fourth place is "alternator problems" - and that's where Vettel really has got a problem.

The two-times world champion ought to have increased his chances of a third title last weekend when he extended his championship lead from 10 points to 13 by finishing second in America. But instead, as the Grand Prix circus arrives in Brazil for the final stop of the season, his odds to be the drivers' champion have actually drifted a fraction to [1.27].

It seems like free money when you think that all Vettel needs is a podium finish (and his odds for that are [1.42], better than his odds to win the title) to secure the title, and he's not been out of the top three for the last six races. But the danger is, now it is all down to one race, he could fail to finish and thus leave the way clear for Fernando Alonso to coast home in third or better.

That's where the worry over the alternator comes in. Incredible that such a common problem for the everyday motorist should scare a Grand Prix team with the resources of Red Bull, but it does. The last time Vettel failed to finish, in Italy, was because the alternator packed up. And that was the exact same reason that Mark Webber had to stop after just 16 laps of the Circuit of the Americas in Austin last week.

Red Bull's team have been working overtime to fix the problem. But even their team principal Christian Horner is talking like one of those mechanics at your local garage who whistles threw his teeth and asks: "Blimey, mate, what cowboy serviced this last time?" Describing the alternator as "a problem", he's said: "It's something that [engine supplier] Renault need to get on top of."

Take all those concerns - and throw in the BBC website's weather forecast that it will be raining in Rio all day on Sunday - and suddenly backing Vettel for the title doesn't seem so safe. It's been arguably the most dramatic F1 season in recent history and you just wonder if there is yet another twist to the tale in store.

That's why I fancy a small bet on two outside chances this weekend - Alonso for the title at [4.7] and Lewis Hamilton to steal a place in the top three of the drivers' championship ahead of Kimi Raikonen at [3.7].

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